Heritability of the algal-foraging ability: an indirect benefit of female mate preference for males' carotenoid-based coloration in the guppy, Poecilia reticulata

Several sexual selection theories assume certain benefits of female mate preference. The direct benefit, i.e., the direct contribution from males to their offspring and females, has been well tested empirically. However, the indirect benefit, i.e., the male's genetic contribution to their offspring, has been poorly demonstrated. Female preference for males' carotenoid-based coloration is known in some animals. Since animals must acquire carotenoids through foods, it is often hypothesized that the brightness of the carotenoid-based coloration is a reliable indicator of the male's foraging ability. Hence, females' indirect benefits, such as greater foraging ability in their offspring, through mate preference for the carotenoid-based coloration are assumed. However, the heritability of the foraging ability for foods that serve as carotenoid resources has not been tested. In this study, a maze experiment was performed in guppies (Poecilia reticulata) to examine the heritability of the foraging ability for algae, carotenoid resources in nature. The latency for completing algal-foraging tasks in this experiment showed high individual variation. Heritable estimates of the foraging ability were substantial (h ² = 0.57 – 0.66) and significant, suggesting a genetic contribution to the foraging ability from fathers to their offspring. This result may support the hypothesis that indirect benefits influence the evolution of female choice.     

A genetic component to size in queens of the ant,<Emphasis Type="Italic"> Formica truncorum</Emphasis>

The genetic basis of morphological traits in social insects remains largely unexplored. This is even true for individual body size, a key life-history trait. In the social insects, the size of reproductive individuals affects dispersal decisions, so that small size in queens is often associated with reduced dispersal, and large size with long-range dispersal and independent colony founding. Worker size is connected to division of labour when workers specialize in certain tasks according to their size. In many species, variation in worker size has been shown to increase colony performance. In this study, we present the first evidence of an additive genetic component to queen size in ants, using maternal half sib analysis. We also compared intra-colony size variation in colonies with high (queen doubly mated) versus low (queen singly mated) genetic variability. We found a high and significant heritability (h²=0.51) for queen size in one of the two study years, but not in the other. Size variation among queens was greater in colonies headed by a doubly mated queen in one of the study years, but not in the other. This indicates that genetic factors can influence queen size, but that environmental factors may override these under some circumstances. The heritability for worker size was low (h²=0.09) and non-significant. Increased genetic diversity did not increase worker size variation in the colonies. Worker size appeared largely environmentally determined, potentially allowing colonies to adjust worker size ratios to current conditions.Communicated by J. Heinze     

Environmental and genetic causes of maturational differences among rhesus macaque matrilines

Females of many cercopithecine primates live in stable dominance hierarchies that create long-term asymmetries among sets of female relatives (matrilines) in access to limiting resources and shelter from psychosocial stress. Rank-related differences in fitness components are widely documented, but their causes are unclear. Predicted breeding values from an animal model for female age of first reproduction are used to discriminate between shared additive genetic and shared environmental effects among the members of matrilines in a population of free-ranging rhesus macaques (Macaca mulatta). While age of first reproduction has a modest heritability (≈0.2), breeding values are distributed in a largely random fashion among matrilines and contribute little to the observed rank-related differences in average age of first reproduction. These results support the long-held, but previously unverified, contention that rank-related life history differences in female cercopithecine primates are the result of environmental rather than genetic differences among them.     

Division of labour and worker size polymorphism in ant colonies: the impact of social and genetic factors

Division of labour among workers is central to the organisation and ecological success of insect societies. If there is a genetic component to worker size, morphology or task preference, an increase in colony genetic diversity arising from the presence of multiple breeders per colony might improve division of labour. We studied the genetic basis of worker size and task preference in Formica selysi, an ant species that shows natural variation in the number of mates per queen and the number of queens per colony. Worker size had a heritable component in colonies headed by a doubly mated queen (h ²=0.26) and differed significantly among matrilines in multiple-queen colonies. However, higher levels of genetic diversity did not result in more polymorphic workers across single- or multiple-queen colonies. In addition, workers from multiple-queen colonies were consistently smaller and less polymorphic than workers from single-queen colonies. The relationship between task, body size and genetic lineage appeared to be complex. Foragers were significantly larger than brood-tenders, which may provide energetic or ergonomic advantages to the colony. Task specialisation was also often associated with genetic lineage. However, genetic lineage and body size were often correlated with task independently of each other, suggesting that the allocation of workers to tasks is modulated by multiple factors. Overall, these results indicate that an increase in colony genetic diversity does not increase worker size polymorphism but might improve colony homeostasis.     

Heritable and experiential effects on boldness in a tropical poeciliid

Consistent differences in human behaviour are often explained with reference to personality traits. Recent evidence suggests that similar traits are widespread across the entire animal kingdom and that they may have substantial fitness consequences. One of the major components of personality is the shyness–boldness continuum. Little is known about the relative contributions of genes and the environment in the development of boldness in wild animal populations. Here, we bred wild-caught fish (Brachyraphis episcopi) collected from regions of high- and low-predation pressure, reared their offspring in the laboratory under varying conditions and tested boldness utilising an open-field paradigm. First-generation laboratory-reared fish showed similar behaviour to their wild parents suggesting that boldness has a heritable component. In addition, repeated chasing with a net increased boldness in both high- and low-predation offspring, showing that boldness is also heavily influenced by life experiences. Differences between males and females were also sustained in the laboratory-reared generation indicating that sex differences in boldness are also heritable. We discuss these results with reference to the potential underlying genetic and hormonal mechanisms as well as the environmental influences that may be responsible for expression of boldness in wild animals.     

Genetic evidence for the “good genes” process of sexual selection

The adaptive nature of female mate choice remains one of the most contentious issues in the study of sexual selection. Here, I provide evidence that mate choice by females of the ovoviviparous cockroach Nauphoeta cinerea influences the rate at which offspring develop and provides both direct and indirect benefits to the female. Males that are more attractive to females produce offspring with shorter development times than less preferred males. Development time is heritable and apparently unconstrained by antagonistic pleiotropy. Male attractiveness and rate of offspring development are genetically correlated. Offspring gain an indirect benefit from their mother's mate choice because, on average, individuals that hatch faster reach sexual maturity more quickly. Females that discriminate among males gain a direct benefit because N. cinerea is ovoviviparous and the time between clutches is decreased by producing offspring with shorter development. In addition to providing evidence for beneficial consequences of mate choice, this study highlights how genetic data provide insights into the process of sexual selection not gained in a purely phenotypic study.Communicated by P. Pamilo     

Foraging ability in the scorpionfly <Emphasis Type="Italic">Panorpa vulgaris</Emphasis>: individual differences and heritability

According to indicator models of sexual selection, mates may obtain indirect, i.e. genetic, benefits from choosing partners indicating high overall genetic quality by honest signals. In the scorpionfly Panorpa vulgaris, both sexes show mating preferences on the basis of the condition of the potential partners. Females prefer males that produce nuptial gifts (i.e. salivary secretions) during copulation, while males invest more nuptial gifts in females of high nutritional status. Both characters, males' ability to produce nuptial gifts and high nutritional status of females, are known to be reliable indicators of foraging ability. Thus, besides possible direct benefits, both sexes might also obtain indirect benefits in terms of “good foraging genes” by their choice and thereby increase the fitness of their offspring. A prerequisite for this possibility is the heritability of the respective trait. In the present study, we estimated the repeatability and the heritability of foraging ability. Our results indicate (1) a significant repeatability of individual foraging efficiencies in males and females and (2) a heritable component of this trait by a significant parent–offspring regression. These findings suggest that genetic benefits in terms of increased offspring foraging ability might contribute to selection for mating preferences in both sexes.     

杉木优良无性系苗造林的效益估算

未来的林业是无性系林业,优良无性系苗造林能把种源选择,种子园的遗传改进、杂交育种、个体选择等成果择其最优部分加以基因复制、利用,从而获得较高的增产效益。本文介绍了12个杉木优良无性系造林后各因子的遗传力和遗传增益。估算了12个优良无性系造林的效益。